The present invention relates to an alarm apparatus for a recirculating exhaust gas flow control device, which device is employed in an internal combustion engine to control the quantity of exhaust gas recirculated through the engine, which gas is introduced to the fuel-air mixture to be sucked into the engine.
It is known to purify an exhaust gas from an internal combustion engine, particularly an automobile engine, by recirculating part of the exhaust gas to the fuel-air mixture to be sucked into the engine. The quantity of recirculation of the exhaust gas is controlled by a flow control device in accordance with the pressure in the fuel-air intake system, such as the carburetor provided for the engine.
If the flow control device for recirculating the exhaust gas fails or otherwise develops difficulties, the driver of the automobile may keep on running the engine for a long time without being aware of the trouble that has developed, because the device does not always have a large and direct influence upon the operation of the engine, and this continued operation after trouble has developed will result in failure to purify the exhaust gas. Accordingly, it is desirable to let the driver know that trouble has developed in the device.